α‑Substituted Bis(octabutoxyphthalocyaninato)Terbium(III) Double-Decker Complexes: Preparation and Study of Protonation by NMR and DFT

Synthesis of the anionic, α-substituted,
bis­(phthalocyaninato)­TbIII complex [Tb­(α-obPc)2] ([1])
(obPc = α-octabutoxyphthalocyaninato) leads to the isolation
of its protonated form [1H]0. This complex
was characterized by X-ray diffraction (XRD), mass spectroscopy (MS),
infrared (IR) and ultraviolet–visible–near-infrared
(UV–vis-NIR) spectroscopy. Crystal structure analysis did not
allow localization of the additional proton, which is probably attached
to the meso-N atom or isoindole-N atom of the phthalocyaninato
ligand. [1H]0 can easily be deprotonated or
protonated, giving the corresponding anionic and cationic complexes.
The three compounds [1H]0, [1], and [1HH]+ were studied
by a combination of paramagnetic NMR experiments (1H, 13C, variable-temperature measurements, two-dimensional nuclear
magnetic resonance and DFT calculations (done on YIII analogues
with octamethoxyphthalocyaninato ligands), for the purpose of elucidating
the positions of the acidic protons and for understanding the structural
changes of the coordination environment of the Tb ion induced by protonation.

阴离子型α-取代双(酞菁合)铽(III)配合物[Tb(α-obPc)₂]⁻（记为[1]⁻，其中obPc代表α-八丁氧基酞菁合配体）的合成过程中，分离得到了其质子化形式[1H]⁰。该配合物通过X射线衍射（XRD）、质谱（MS）、红外（IR）以及紫外-可见-近红外（UV-vis-NIR）光谱进行了表征。晶体结构分析未能定位该额外质子，其大概率结合于酞菁合配体的中位氮原子或异吲哚氮原子上。[1H]⁰可轻易发生去质子化或质子化反应，分别得到对应的阴离子与阳离子配合物。为阐明酸性质子的结合位置，并理解质子化作用对铽离子配位环境造成的结构变化，研究人员结合顺磁核磁共振实验（包括¹H、¹³C谱、变温测量、二维核磁共振）以及密度泛函理论（DFT）计算（针对带有八甲氧基酞菁合配体的钇(III)类似物展开），对[1H]⁰、[1]⁻与[1HH]⁺三种化合物进行了研究。